This article explores the role of ‘colonial common sense’ ( Stoler, 2008) in racialising men of colour in capital cases in twentieth-century England and Wales. Following the First World War psychiatric and psychological discourses became more prominent in both the criminal justice system and the wider culture, but were not the primary means through which race was constructed in capital trials. Rather, colonially informed common sense understandings of racial difference were more significant and were themselves an aspect of medical expertise, such as prison medicine. The article discusses cases such as Djang Djin Sung, the first man of colour to be executed in England after the First World War, Lock Ah Tam, who was hanged in 1926 despite benefiting from a well-funded insanity defence and Eric Dique, who murdered his girlfriend in 1956. Analysis of cases of men of colour sentenced to death in this period contributes to uncovering the history of racism in the criminal justice system.